/*
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at 
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *  
 */

using System;
using java = biz.ritter.javapi;
using org.apache.commons.collections;

namespace org.apache.commons.collections
{

    /**
     * Defines a collection for priority queues, which can insert, peek and pop.
     * <p>
     * This interface is now replaced by the <code>Buffer</code> interface.
     *
     * @deprecated Replaced by the Buffer interface and implementations in buffer subpackage.
     *  Due to be removed in v4.0.
     * @since Commons Collections 1.0
     * @version $Revision: 7130 $ $Date: 2011-06-04 20:48:14 +0200 (Sa, 04. Jun 2011) $
     * 
     * @author Peter Donald
     */
    public interface PriorityQueue
    {

        /**
         * Clear all elements from queue.
         */
        void clear();

        /**
         * Test if queue is empty.
         *
         * @return true if queue is empty else false.
         */
        bool isEmpty();

        /**
         * Insert an element into queue.
         *
         * @param element the element to be inserted
         *
         * @throws ClassCastException if the specified <code>element</code>'s
         * type prevents it from being compared to other items in the queue to
         * determine its relative priority.  
         */
        void insert(Object element);

        /**
         * Return element on top of heap but don't remove it.
         *
         * @return the element at top of heap
         * @throws java.util.NoSuchElementException if <code>isEmpty() == true</code>
         */
        Object peek();

        /**
         * Return element on top of heap and remove it.
         *
         * @return the element at top of heap
         * @throws java.util.NoSuchElementException if <code>isEmpty() == true</code>
         */
        Object pop();

    }
}
